The present invention relates to a data communication apparatus, a data communication system, and a data communication method, and particularly to an improvement in safety (on security).
Data communication systems using non-contact type IC cards have been utilized for transaction with prepaid cards, for automatic toll collecting at ski lifts and trains, and for automatic package control. FIG. 25 shows a configuration of a data communication system utilizing a non-contact type IC card. This system consists of a reader/writer 2 (placed at a ski lift gate, for example) and a non-contact IC card 20.
Reader/writer 2 transmits high-frequency carrier waves from an oscillation circuit 10 via an antenna 4, under the control of a control unit 8. When non-contact IC card 20 comes close to reader/writer 2, an antenna 24 of non-contact IC card 20 receives the high-frequency carrier waves. A power supplying circuit 28 converts the received high-frequency waves to direct-current power that is to be supplied to other circuit portions. Non-contact IC card 20 is thus activated when it approaches reader/writer 2. The power supplying circuit 28, a modulator/demodulator circuit 30, a control unit 32, and a non-volatile memory 34 are configured as an IC chip 36 to save space.
For data transmission from reader/writer 2 to non-contact IC card 20, a modulator/demodulator circuit 6 first modulates the high-frequency carrier waves under the control of control unit 8. In non-contact IC card 20, modulator/demodulator circuit 30 demodulates the modulated high-frequency carrier waves. Control unit 32 receives the demodulated data and performs necessary processes, such as rewriting the content of a non-volatile memory 34 and returning the data.
Data transmission in the opposite direction from non-contact IC card 20 to reader/writer 2 is also performed. Here, non-contact IC card 20 is not provided with an oscillation circuit. Thus, utilizing unmodulated, high-frequency carrier waves sent from reader/writer 2, modulator/demodulator 30 at non-contact IC card 20 changes impedance of a resonance circuit 22 on the card side. Reader/writer 2 regards this impedance change as an impedance change in a resonance circuit 12 on its own side, and detects and demodulates this impedance change by modulator/demodulator circuit 6. Control unit 8 receives the demodulated data and performs necessary processes.
When non-contact IC card 20 moves away from reader/writer 2, it is no longer provided with power, and thus, card 20 terminates its operation. Without the power supply, however, stored data are maintained because non-volatile memory 34 is used.
As described above, with the data communication system using IC card 20, it is possible to transmit data in a non-contact manner, without having to include a power source within the card.
The above data communication system using a conventional IC card 20, however, exhibits the following problem.
In the data communication system using the conventional IC card 20, original data are used as communication data between reader/writer 2 and IC card 20 to keep the manufacturing cost of the system low. Therefore, it is relatively easy for a third party to read the data being communicated. Inevitably, such a system is regarded unsuitable for communicating data requiring secret protection.
To transmit such data requiring secrecy, there is a data communication system in which data are encrypted with a complicated technique before being communicated. For such an encryption, however, a complex, large-scale apparatus is required. This increases the manufacturing cost of the system.
An object of the present invention is to provide a data communication apparatus, a data communication system, and a data communication method, that achieve high level of safety on security at low cost.
The data communication apparatus, system and method according to the present invention are configured to select one of a plurality of conversion methods for conversion between original data and processed data and designate it as a conversion method to be executed, in accordance with a prescribed condition that may be altered and can be commonly recognized with another data communication apparatus.
In summary, the present invention is directed to a data communication apparatus that is provided with a data communication unit, a conversion method designating unit, and a data converting unit.
The data communication unit performs communication of processed data with another data communication apparatus.
The conversion method designating unit selects one of a plurality of conversion methods for conversion between original data and processed data and designates it as a conversion method to be executed, corresponding to a prescribed condition that may be altered and can be commonly recognized with another data communication apparatus.
The data converting unit converts processed data obtained from the data communication unit to original data, or converts original data to processed data to apply to the data communication unit.
The data communication apparatus performs conversion between original data and processed data according to the same conversion method as used in the other data communication apparatus.
According to another aspect of the present invention, a data communication system is provided which performs communication of processed data between one and another data communication apparatuses. This data communication system is configured such that the conversion methods designated for both the data communication apparatuses are the same.
The data communication apparatus is provided with: a first data communication unit that performs communication of processed data with the other data communication apparatus; a first conversion method designating unit that selects one of a plurality of conversion methods for conversion between original data and processed data and designates it as a conversion method to be executed, corresponding to a prescribed condition that may be altered and can be commonly recognized with the other data communication apparatus; and a first data converting unit that converts processed data obtained from the data communication unit to original data, or converts original data to processed data to apply to the first data communication unit, according to the conversion method designated by the first conversion method designating unit.
The other data communication apparatus is provided with: a second data communication unit that performs communication of processed data with the data communication apparatus; a second conversion method designating unit that selects, according to a prescribed condition, one of a plurality of conversion methods for conversion between original data and processed data and designates it as a conversion method to be executed; and a second data converting unit that converts processed data obtained from the second data communication unit to original data, or converts original data to processed data to apply to the second data communication unit, according to the conversion method designated by the second conversion method designating unit.
According to a further aspect of the present invention, a data communication method for performing communication of processed data between at least two data communication apparatuses is provided. The method includes: the step of selecting one of a plurality of conversion methods for conversion between original data and processed data and designating the same as a conversion method to be executed, according to a prescribed condition that may be altered and can be commonly recognized with other data communication apparatuses; and the step of converting processed data received from the other data communication apparatus to original data, or converting original data to processed data to apply to the other data communication apparatus. Here, the conversion methods designated at respective data communication apparatuses are to be made the same.
Accordingly, a main advantage of the present invention is that a conversion method to be executed can be altered as a prescribed condition changes, thereby making it difficult to determine which conversion method is currently utilized for data conversion. As a result, it is possible to improve the level of safety on security on data during data communication. In addition, the present invention is configured such that a conversion method to be executed is selected from a plurality of conversion methods according to the variable condition described above. Thus, even when each conversion method being prepared is relatively simple, the high level of safety on security can be maintained during data communication. Accordingly, it is unnecessary to provide complex large-scale equipment as in the case where data are to be encrypted using a complicated technique. The manufacturing cost of the apparatus and system thus can be restricted.